Improvement in methods of casting metals



Uterine STATES ,PATENT Ferca.,

JACQUES RIVES, OF PARIS, FRANCE.

IMPROVEMENT IN METHODS OF CASTING METALS.

Specification forming part of Letters Patent No. 82,642, dated September29, 1868.

To all whom it may concern:

Beitknown thatI, J. RIVEs,of Paris, France, have invented an Improvementin Casting Metals, Glass, Src.; and I4 do hereby declare the followingto be a full, clear, and exact description ot' the same.

My invention consists, first, of apparatus for subjecting a body ot'metal or other material while in a state of fusion and during theprocess ot' cooling:| to the action of a gas under pressure, as fullydescribed hereinafter, an iugot or casting of uniform density being thusproduced.

In order to enable others skilled in the art to make and use myinvention, I will now proceed to describe the manner of carrying it intoeffect, reference heilig had to the accompanying drawings, which form apart of this specication, and in which- Figure 1 is a sectionalelevation ot' my improved apparatus; Fig. 2, a detached view of part ofthe apparatus.

A is a strong metal vessel, on which are metal bands a a., and which isarranged within a larger vessel or tank, o, containing water, the VesselA communicating through a pipe, 1', (having cocks R R and a 1)ressure-gage, F,) with a reservoir, I, containing air or other suitablegas under pressure.

To the vessel A is fitted a cap, B, between which and the vessel is asoft-metal washer,'m,

the cap being secured in its place by a screw, V, which passes through ayoke, u, and bears with its lower end upon the cap, the yoke havingarmswith projections o at their lower ends,

which projections catch beneath lugs o on blocks P, bolted to the upperbanda. A second yoke, n', the arms of which are bolted to the cap B,extends over the yoke n, and con-y nects the latter to-the cap withoutpreventing the yoke from being turned slightly, independently of thecap, to more the projections c from beneath the lugs o.

To the upper end of the screw V are secured a. handle, l", and a pulley,t, and round the latter passes a chain, E, by which the cap can beraised and lowered.

Within the vessel A is a mold, L, for thereception of molten metal, themold being placed within a perforated casing, T, which is sli ghtl ygreater in diameter than the mold, so that there is an annular spacebetween the two. To the mold is fitted a cap, D, of earthenware or otherrefractory material, and the space between the casing T and the innerside of the vessel Ais filled with wood-charcoal in lumps of such a sizeas to permit the free passage of air between them.

It is well knownthat when any material is cast the upper portions areless dense than the lower, the same quality belonging to all fluids',whether liquid or gaseous, and consequently to solid bodies in a stateot' fusion; but the latter retain after fusion the density which wastheirs in .a liquid state, and consequently the mass is not homogeneous.When, however, the fused material is subjected to a uniform pressure,it-will on 'cooling be of an equal density throughout. This fact is wellknown to found` ers, who apply it in using what they call the lump.7Thus, when they wish to havea dense, homogeneous, and flawless casting,they surcharge the mold with matter to compress the molten contents; butthe utility of this method isvery limited, the pressure, though varyingwith the importance of the casting, being seldom very great. By theimproved process, which I will now proceed to describe, homogeneouscastings of any desired degree of density may be obtained:

Let it be supposed that the air or gas reser- Voir I is filled to apressure of ten atmospheres, that the vessel A is open, and that steel,glass, or otherfmaterial is to be cast. The molten material is pouredinto the mold L, a small iron disk, D', is placed over the fused matter,and the mold L is covered by the cap `D. j As soon as the vessel hasacquired the temperature of the molten material the radiating heattraverses the thin stratum of air between the mold and the easing T,heats the latter, and renders incandescent thecharcoal surroundin g it.The cap is then lowered and tightly secured, closing the apparatusair-tight, after which the cock lt is opened, and compressed air isadmitted among the interstices of the charcoal. At first there is auequilibriumgof pressure; but soon the air in the vessel A becomesdilated, a portion returns to the reservoir, and the equilibrium isagain established. If the cock is closed when Ythe air has entered thevessel A, thev pressure in the latter will be greater than in thereservoir. The pressure can thus by means ofthe cock be regulated atwill. The quantity of air which penetrates the apparatus is relativelysmall, since the vessel A is almost entirely illed by the mold, itscontents, and the charcoal, the air used is thus economized, and theheat is concentrated in a small space. The cooling should be effectedslowly and as regularly as possible, this result being obtained by thewater surrounding the vessel A, which concentrates the heat, so thatsucient time is afforded for the molecules of matter to approach eachother, and a dense ingot is obtained, because the pressure whichoperated upon the fused matter operates upon it during ull the degreesof cooling.

The material cast i'n this apparatus is subjected to a considerablepressure, ten atmosphces-correspondin g to a column of cast-steel

